1. Field of the Invention
The invention is directed to a single-stage vane compressor with a water-cooled cover.
2. Description of the Prior Art
Single-stage water-cooled vane-type compressors are known generally and are used for various purposes, e.g., for suction vehicles and stationary installations (see brochure from the Mannesmann Demag company, "Demag-Wittig compressor vacuum pump for suction vehicles and stationary installations", October 1986, pages 10 to 14). These water-cooled vane compressors have a casing provided with feet and a cooling water jacket. A rotor which is provided with radially movable slides is arranged in this casing so as to be off-center with respect to the casing bore hole and its shaft journal is supported in bearings by covers arranged at the end faces of the casing. Flanges for sucking out and ejecting the medium are arranged at the casing jacket so as to be offset along the circumference. This construction, which has been in use for years, has the disadvantage of sharp variations in temperature distribution along the circumference and larger sealing gaps must be provided because of distortion in the casing. However, larger sealing gaps are a sign of poor efficiency, since the magnitude of the sealing gap has a very substantial influence on efficiency due to power loss.
DE-OS 1403608 discloses a water-cooled single-stage vane compressor of the generic type in which the cooled casing jacket is divided into ducts by substantially longitudinal walls distributed along the circumference. In one embodiment, one of the longitudinal walls has no opening, the inlet for cooling water being arranged on one side of the dividing wall while the outlet is arranged on the other side. In this way, the cooling water is compelled to run along a zigzag path through the casing jacket. In another construction, the jacket space is divided into two through-flow systems by a transverse wall disposed vertically to the axis of rotation. This construction has the disadvantage that the elevated temperature level prevailing in the delivery region is influenced only negligibly by the suggested arrangement of the cooling ducts.
DE-OS 36 03 809 describes a two-stage vane compressor in which the rotor axis is arranged symmetrically to the outer contour of the casing. The covers and casing jacket are liquid-cooled and the coolant space is not divided. Therefore, the temperature distribution varies sharply along the circumference and larger sealing gaps must be provided because of the distortion of the casing.